Sacrifical Anode: An easily corroded material deliberately installed
in a pipe or intake to give it up (sacrifice it) to corrosion while the
rest of the water supply facility remains relatively corrosion-free.

Safe: Condition of exposure under which there is a practical certainty
that no harm will result to exposed individuals.

Safe Water: Water that does not contain harmful bacteria, toxic
materials, or chemicals, and is considered safe for drinking even if it
may have taste, odor, color, and certain mineral problems.

Safe Yield: The annual amount of water that can be taken from
a source of supply over a period of years without depleting that source
beyond its ability to be replenished naturally in "wet years."

Safener: A chemical added to a pesticide to keep it from injuring
plants.

Salinity: The percentage of salt in water.

Salt Water Intrusion: The invasion of fresh surface or ground
water by salt water. If it comes from the ocean it may be called sea water
intrusion.

Salts: Minerals that water picks up as it passes through the air,
over and under the ground, or from households and industry.

Salvage: The utilization of waste materials.

Sampling Frequency: The interval between the collection of successive
samples.

Sanctions: Actions taken by the federal government for failure
to provide or implement a State Implementation Plan (SIP). Such action
may include withholding of highway funds and a ban on construction of
new sources of potential pollution.

Sand Filters: Devices that remove some suspended solids from sewage.
Air and bacteria decompose additional wastes filtering through the sand
so that cleaner water drains from the bed.

Sanitary Sewers: Underground pipes that carry off only domestic
or industrial waste, not storm water.

Sanitary Survey: An on-site review of the water sources, facilities,
equipment, operation and maintenance of a public water system to evaluate
the adequacy of those elements for producing and distributing safe drinking
water.

Sanitary Water (Also known as gray water): Water discharged from
sinks, showers, kitchens, or other non-industrial operations, but not
from commodes.

Sanitation: Control of physical factors in the human environment
that could harm development, health, or survival.

Saprolite: A soft, clay-rich, thoroughly decomposed rock formed
in place by chemical weathering of igneous or metamorphic rock. Forms
in humid, tropical, or subtropical climates.

Saprophytes: Organisms living on dead or decaying organic matter
that help natural decomposition of organic matter in water.

Saturated Zone: The area below the water table where all open
spaces are filled with water under pressure equal to or greater than that
of the atmosphere.

Saturation: The condition of a liquid when it has taken into solution
the maximum possible quantity of a given substance at a given temperature
and pressure.

Science Advisory Board (SAB): A group of external scientists who
advise EPA on science and policy.

Scrap: Materials discarded from manufacturing operations that
may be suitable for reprocessing.

Screening: Use of screens to remove coarse floating and suspended
solids from sewage.

Screening Risk Assessment: A risk assessment performed with few
data and many assumptions to identify exposures that should be evaluated
more carefully for potential risk.

Scrubber: An air pollution device that uses a spray of water or
reactant or a dry process to trap pollutants in emissions.

Secondary Drinking Water Regulations: Non-enforceable regulations
applying to public water systems and specifying the maximum contamination
levels that, in the judgment of EPA, are required to protect the public
welfare. These regulations apply to any contaminants that may adversely
affect the odor or appearance of such water and consequently may cause
people served by the system to discontinue its use.

Secondary Effect: Action of a stressor on supporting components
of the ecosystem, which in turn impact the ecological component of concern.
(See: primary effect.)

Secondary Materials: Materials that have been manufactured and
used at least once and are to be used again.

Secondary Treatment: The second step in most publicly owned waste
treatment systems in which bacteria consume the organic parts of the waste.
It is accomplished by bringing together waste, bacteria, and oxygen in
trickling filters or in the activated sludge process. This treatment removes
floating and settleable solids and about 90 percent of the oxygen-demanding
substances and suspended solids. Disinfection is the final stage of secondary
treatment. (See: primary, tertiary treatment.)

Secure Maximum Contaminant Level: Maximum permissible level of
a contaminant in water delivered to the free flowing outlet of the ultimate
user, or of contamination resulting from corrosion of piping and plumbing
caused by water quality.

Sediment: Topsoil, sand, and minerals washed from the land into water, usually after rain or snow melt.

Sediment Yield: The quantity of sediment arriving at a specific
location.

Sedimentation: Letting solids settle out of wastewater by gravity
during treatment.

Sedimentation Tanks: Wastewater tanks in which floating wastes
are skimmed off and settled solids are removed for disposal.

Sediments: Soil, sand, and minerals washed from land into water,
usually after rain. They pile up in reservoirs, rivers and harbors, destroying
fish and wildlife habitat, and clouding the water so that sunlight cannot
reach aquatic plants. Careless farming, mining, and building activities
will expose sediment materials, allowing them to wash off the land after
rainfall.

Seed Protectant: A chemical applied before planting to protect
seeds and seedlings from disease or insects.

Seepage: Percolation of water through the soil from unlined canals,
ditches, laterals, watercourses, or water storage facilities.

Selective Pesticide: A chemical designed to affect only certain
types of pests, leaving other plants and animals unharmed.

Semi-Confined Aquifer: An aquifer partially confined by soil layers
of low permeability through which recharge and discharge can still occur.

Senescence: The aging process. Sometimes used to describe lakes
or other bodies of water in advanced stages of eutrophication. Also used
to describe plants and animals.

Septic System: An on-site system designed to treat and dispose
of domestic sewage. A typical septic system consists of tank that receives
waste from a residence or business and a system of tile lines or a pit
for disposal of the liquid effluent (sludge) that remains after decomposition
of the solids by bacteria in the tank and must be pumped out periodically.

Septic Tank: An underground storage tank for wastes from homes
not connected to a sewer line. Waste goes directly from the home to the
tank. (See: septic system.)

Service Connector: The pipe that carries tap water from a public
water main to a building.

Service Line Sample: A one-liter sample of water that has been
standing for at least 6 hours in a service pipeline and is collected according
to federal regulations.

Service Pipe: The pipeline extending from the water main to the
building served or to the consumer's system.

Set-Back: Setting a thermometer to a lower temperature when the
building is unoccupied to reduce consumption of heating energy. Also refers
to setting the thermometer to a higher temperature during unoccupied periods
in the cooling season.

Settleable Solids: Material heavy enough to sink to the bottom
of a wastewater treatment tank.

Settling Chamber: A series of screens placed in the way of flue
gases to slow the stream of air, thus helping gravity to pull particles
into a collection device.

Settling Tank: A holding area for wastewater, where heavier particles
sink to the bottom for removal and disposal.

7Q10: Seven-day, consecutive low flow with a ten year return frequency;
the lowest stream flow for seven consecutive days that would be expected
to occur once in ten years.

Sewage: The waste and wastewater produced by residential and commercial
sources and discharged into sewers.

Sewerage: The entire system of sewage collection, treatment, and
disposal.

Shading Coefficient: The amount of the sun's heat transmitted
through a given window compared with that of a standard 1/8- inch-thick
single pane of glass under the same conditions.

Sharps: Hypodermic needles, syringes (with or without the attached
needle), Pasteur pipettes, scalpel blades, blood vials, needles with attached
tubing, and culture dishes used in animal or human patient care or treatment,
or in medical, research or industrial laboratories. Also included are
other types of broken or unbroken glassware that were in contact with
infectious agents, such as used slides and cover slips, and unused hypodermic
and suture needles, syringes, and scalpel blades.

Shock Load: The arrival at a water treatment plant of raw water
containing unusual amounts of algae, colloidal matter. color, suspended
solids, turbidity, or other pollutants.

Short-Circuiting: When some of the water in tanks or basins flows
faster than the rest; may result in shorter contact, reaction, or settling
times than calculated or presumed.

Sick Building Syndrome: Building whose occupants experience acute
health and/or comfort effects that appear to be linked to time spent therein,
but where no specific illness or cause can be identified. Complaints may
be localized in a particular room or zone, or may spread throughout the
building. (See: building-related illness.)

Signal: The volume or product-level change produced by a leak
in a tank.

Signal Words: The words used on a pesticide label--Danger, Warning,
Caution--to indicate level of toxicity.

Significant Municipal Facilities: Those publicly owned sewage
treatment plants that discharge a million gallons per day or more and
are therefore considered by states to have the potential to substantially
affect the quality of receiving waters.

Significant Potential Source of Contamination: A facility or activity
that stores, uses, or produces compounds with potential for significant
contaminating impact if released into the source water of a public water
supply.

Significant Violations: Violations by point source dischargers
of sufficient magnitude or duration to be a regulatory priority.

Single-Breath Canister: Small one-liter canister designed to capture
a single breath. Used in air pollutant ingestion research.

Sink: Place in the environment where a compound or material collects.

Sinking: Controlling oil spills by using an agent to trap the
oil and sink it to the bottom of the body of water where the agent and
the oil are biodegraded.

SIP Call: EPA action requiring a state to resubmit all or part
of its State Implementation Plan to demonstrate attainment of the require
national ambient air quality standards within the statutory deadline.
A SIP Revision is a revision of a SIP altered at the request of EPA or
on a state's initiative. (See: State Implementation
Plan.)

Site: An area or place within the jurisdiction of the EPA and/or
a state.

Site Assessment Program: A means of evaluating hazardous waste
sites through preliminary assessments and site inspections to develop
a Hazard Ranking System score.

Site Inspection: The collection of information from a Superfund
site to determine the extent and severity of hazards posed by the site.
It follows and is more extensive than a preliminary assessment. The purpose
is to gather information necessary to score the site, using the Hazard
Ranking System, and to determine if it presents an immediate threat requiring
prompt removal.

Site Safety Plan: A crucial element in all removal actions, it
includes information on equipment being used, precautions to be taken,
and steps to take in the event of an on-site emergency.

Siting: The process of choosing a location for a facility.

Skimming: Using a machine to remove oil or scum from the surface
of the water.

Slow Sand Filtration: Passage of raw water through a bed of sand
at low velocity, resulting in substantial removal of chemical and biological
contaminants.

Sludge: A semi-solid residue from any of a number of air or water
treatment processes; can be a hazardous waste.

Sludge Digester: Tank in which complex organic substances like
sewage sludges are biologically dredged. During these reactions, energy
is released and much of the sewage is converted to methane, carbon dioxide,
and water.

Slurry: A watery mixture of insoluble matter resulting from some
pollution control techniques.

Small Quantity Generator (SQG-sometimes referred to as "Squeegee"):
Persons or enterprises that produce 220-2200 pounds per month of hazardous
waste; they are required to keep more records than conditionally exempt
generators. The largest category of hazardous waste generators, SQGs,
include automotive shops, dry cleaners, photographic developers, and many
other small businesses. (See: conditionally exempt
generators.)

Smelter: A facility that melts or fuses ore, often with an accompanying
chemical change, to separate its metal content. Emissions cause pollution.
"Smelting" is the process involved.

Soft Water: Any water that does not contain a significant amount
of dissolved minerals such as salts of calcium or magnesium.

Soil Adsorption Field: A sub-surface area containing a trench
or bed with clean stones and a system of piping through which treated
sewage may seep into the surrounding soil for further treatment and disposal.

Soil and Water Conservation Practices: Control measures consisting
of managerial, vegetative, and structural practices to reduce the loss
of soil and water.

Soil Conditioner: An organic material like humus or compost that
helps soil absorb water, build a bacterial community, and take up mineral
nutrients.

Soil Erodibility: An indicator of a soil's susceptibility to raindrop
impact, runoff, and other erosive processes.

Soil Gas: Gaseous elements and compounds in the small spaces between
particles of the earth and soil. Such gases can be moved or driven out
under pressure.

Soil Moisture: The water contained in the pore space of the unsaturated
zone.

Soil Sterilant: A chemical that temporarily or permanently prevents
the growth of all plants and animals,

Solder: Metallic compound used to seal joints between pipes. Until
recently, most solder contained 50 percent lead. Use of solder containing
more than 0.2 percent lead in pipes carrying drinking water is now prohibited.

Sole-Source Aquifer: An aquifer that supplies 50-percent or more
of the drinking water of an area.

Solid Waste Disposal: The final placement of refuse that is not
salvaged or recycled.

Solid Waste Management: Supervised handling of waste materials
from their source through recovery processes to disposal.

Solidification and Stabilization: Removal of wastewater from a
waste or changing it chemically to make it less permeable and susceptible
to transport by water.

Solubility: The amount of mass of a compound that will dissolve
in a unit volume of solution. Aqueous Solubility is the maximum concentration
of a chemical that will dissolve in pure water at a reference temperature.

Soot: Carbon dust formed by incomplete combustion.

Sorption: The action of soaking up or attracting substances; process
used in many pollution control systems.

Source Area: The location of liquid hydrocarbons or the zone of
highest soil or groundwater concentrations, or both, of the chemical of
concern.

Source Characterization Measurements: Measurements made to estimate
the rate of release of pollutants into the environment from a source such
as an incinerator, landfill, etc.

Source Reduction: Reducing the amount of materials entering the
waste stream from a specific source by redesigning products or patterns
of production or consumption (e.g., using returnable beverage containers).
Synonymous with waste reduction.

Source Separation: Segregating various wastes at the point of
generation (e.g., separation of paper, metal and glass from other wastes
to make recycling simpler and more efficient).

Source-Water Protection Area: The area delineated by a state for
a Public Water Supply or including numerous such suppliers, whether the
source is ground water or surface water or both.

Sparge or Sparging: Injection of air below the water table to
strip dissolved volatile organic compounds and/or oxygenate ground water
to facilitate aerobic biodegradation of organic compounds.

Special Local-Needs Registration: Registration of a pesticide
product by a state agency for a specific use that is not federally registered.
However, the active ingredient must be federally registered for other
uses. The special use is specific to that state and is often minor, thus
may not warrant the additional cost of a full federal registration process.
SLN registration cannot be issued for new active ingredients, food-use
active ingredients without tolerances, or for a canceled registration.
The products cannot be shipped across state lines.

Special Review: Formerly known as Rebuttable Presumption Against
Registration (RPAR), this is the regulatory process through which existing
pesticides suspected of posing unreasonable risks to human health, non-target
organisms, or the environment are referred for review by EPA. Such review
requires an intensive risk/benefit analysis with opportunity for public
comment. If risk is found to outweigh social and economic benefits, regulatory
actions can be initiated, ranging from label revisions and use-restriction
to cancellation or suspended registration.

Special Waste: Items such as household hazardous waste, bulky
wastes (refrigerators, pieces of furniture, etc.) tires, and used oil.

Species: 1. A reproductively isolated aggregate of interbreeding
organisms having common attributes and usually designated by a common
name.2. An organism belonging to belonging to such a category.

Specific Conductance: Rapid method of estimating the dissolved
solid content of a water supply by testing its capacity to carry an electrical
current.

Specific Yield: The amount of water a unit volume of saturated
permeable rock will yield when drained by gravity.

Spill Prevention, Containment, and Countermeasures Plan (SPCP):
Plan covering the release of hazardous substances as defined in the Clean
Water Act.

Spoil: Dirt or rock removed from its original location--destroying
the composition of the soil in the process--as in strip-mining, dredging,
or construction.

Sprawl: Unplanned development of open land.

Spray Tower Scrubber: A device that sprays alkaline water into
a chamber where acid gases are present to aid in neutralizing the gas.

Spring: Ground water seeping out of the earth where the water
table intersects the ground surface.

Spring Melt/Thaw: The process whereby warm temperatures melt winter
snow and ice. Because various forms of acid deposition may have been stored
in the frozen water, the melt can result in abnormally large amounts of
acidity entering streams and rivers, sometimes causing fish kills.

Stabilization: Conversion of the active organic matter in sludge
into inert, harmless material.

Stable Air: A motionless mass of air that holds, instead of dispersing,
pollutants.

Stack: A chimney, smokestack, or vertical pipe that discharges
used air.

Stack Effect: Air, as in a chimney, that moves upward because
it is warmer than the ambient atmosphere.

Stack Effect: Flow of air resulting from warm air rising, creating
a positive pressure area at the top of a building and negative pressure
area at the bottom. This effect can overpower the mechanical system and
disrupt building ventilation and air circulation.

Stage II Controls: Systems placed on service station gasoline
pumps to control and capture gasoline vapors during refuelling.

Stagnation: Lack of motion in a mass of air or water that holds
pollutants in place.

Stakeholder: Any organization, governmental entity, or individual
that has a stake in or may be impacted by a given approach to environmental
regulation, pollution prevention, energy conservation, etc.

Standard Industrial Classification Code: Also known as SIC Codes, a method of grouping industries with similar products or services and assigning codes to these groups.

Standard Sample: The part of finished drinking water that is examined
for the presence of coliform bacteria.

Standards: Norms that impose limits on the amount of pollutants
or emissions produced. EPA establishes minimum standards, but states are
allowed to be stricter.

Start of a Response Action: The point in time when there is a
guarantee or set-aside of funding by EPA, other federal agencies, states
or Principal Responsible Parties in order to begin response actions at
a Superfund site.

State Emergency Response Commission (SERC): Commission appointed
by each state governor according to the requirements of SARA Title III.
The SERCs designate emergency planning districts, appoint local emergency
planning committees, and supervise and coordinate their activities.

State Environmental Goals and Indication Project: Program to assist
state environmental agencies by providing technical and financial assistance
in the development of environmental goals and indicators.

State Implementation Plans (SIP): EPA approved state plans for
the establishment, regulation, and enforcement of air pollution standards.

State Management Plan: Under FIFRA, a state management plan required
by EPA to allow states, tribes, and U.S. territories the flexibility to
design and implement ways to protect ground water from the use of certain
pesticides.

Static Water Depth: The vertical distance from the centerline
of the pump discharge down to the surface level of the free pool while
no water is being drawn from the pool or water table.

Static Water Level: 1. Elevation or level of the water table in
a well when the pump is not operating. 2. The level or elevation to which
water would rise in a tube connected to an artesian aquifer or basin in
a conduit under pressure.

Stationary Source: A fixed-site producer of pollution, mainly
power plants and other facilities using industrial combustion processes.
(See: point source.)

Sterilization: The removal or destruction of all microorganisms,
including pathogenic and other bacteria, vegetative forms, and spores.

Sterilizer: One of three groups of anti-microbials registered
by EPA for public health uses. EPA considers an antimicrobial to be a
sterilizer when it destroys or eliminates all forms of bacteria, viruses,
and fungi and their spores. Because spores are considered the most difficult
form of microorganism to destroy, EPA considers the term sporicide to
be synonymous with sterilizer.

Storm Sewer: A system of pipes (separate from sanitary sewers)
that carries water runoff from buildings and land surfaces.

Stratification: Separating into layers.

Stratigraphy: Study of the formation, composition, and sequence
of sediments, whether consolidated or not.

Stratosphere: The portion of the atmosphere 10-to-25 miles above
the earth's surface.

Stressors: Physical, chemical, or biological entities that can
induce adverse effects on ecosystems or human health.

Strip-Cropping: Growing crops in a systematic arrangement of strips
or bands that serve as barriers to wind and water erosion.

Strip-Mining: A process that uses machines to scrape soil or rock
away from mineral deposits just under the earth's surface.

Structural Deformation: Distortion in walls of a tank after liquid
has been added or removed.

Subchronic: Of intermediate duration, usually used to describe
studies or periods of exposure lasting between 5 and 90 days.

Subchronic Exposure: Multiple or continuous exposures lasting
for approximately ten percent of an experimental species lifetime, usually
over a three-month period.

Submerged Aquatic Vegetation: Vegetation that lives at or below
the water surface; an important habitat for young fish and other aquatic
organisms.

Subwatershed: Topographic perimeter of the catchment area of a
stream tributary.

Sulfur Dioxide (SO2): A pungent, colorless, gasformed primarily
by the combustion of fossil fuels; becomes a pollutant when present in
large amounts.

Sump: A pit or tank that catches liquid runoff for drainage or
disposal.

Superchlorination: Chlorination with doses that are deliberately
selected to produce water free of combined residuals so large as to require
dechlorination.

Supercritical Water: A type of thermal treatment using moderate
temperatures and high pressures to enhance the ability of water to break
down large organic molecules into smaller, less toxic ones. Oxygen injected
during this process combines with simple organic compounds to form carbon
dioxide and water.

Superfund: The program operated under the legislative authority
of CERCLA and SARA that funds and carries out EPA solid waste emergency
and long-term removal and remedial activities. These activities include
establishing the National Priorities List, investigating sites for inclusion
on the list, determining their priority, and conducting and/or supervising
cleanup and other remedial actions.

Superfund Innovative Technology Evaluation (SITE) Program: EPA
program to promote development and use of innovative treatment and site
characterization technologies in Superfund site cleanups.

Supplemental Registration: An arrangement whereby a registrant
licenses another company to market its pesticide product under the second
company's registration.

Supplier of Water: Any person who owns or operates a public water
supply.

Surface Runoff: Precipitation, snow melt, or irrigation water
in excess of what can infiltrate the soil surface and be stored in small
surface depressions; a major transporter of non-point source pollutants
in rivers, streams, and lakes..

Surface-Water Treatment Rule: Rule that specifies maximum contaminant
level goals for Giardia lamblia, viruses, and Legionella and promulgates
filtration and disinfection requirements for public water systems using
surface-water or ground-water sources under the direct influence of surface
water. The regulations also specify water quality, treatment, and watershed
protection criteria under which filtration may be avoided.

Surfacing ACM: Asbestos-containing material that is sprayed or
troweled on or otherwise applied to surfaces, such as acoustical plaster
on ceilings and fireproofing materials on structural members.

Surfacing Material: Material sprayed or troweled onto structural
members (beams, columns, or decking) for fire protection; or on ceilings
or walls for fireproofing, acoustical or decorative purposes. Includes
textured plaster, and other textured wall and ceiling surfaces.

Surfactant: A detergent compound that promotes lathering.

Surrogate Data: Data from studies of test organisms or a test
substance that are used to estimate the characteristics or effects on
another organism or substance.

Surveillance System: A series of monitoring devices designed to
check on environmental conditions.

Susceptibility Analysis: An analysis to determine whether a Public
Water Supply is subject to significant pollution from known potential
sources.

Suspended Loads: Specific sediment particles maintained in the
water column by turbulence and carried with the flow of water.

Suspended Solids: Small particles of solid pollutants that float
on the surface of, or are suspended in, sewage or other liquids. They
resist removal by conventional means.

Suspension: Suspending the use of a pesticide when EPA deems it
necessary to prevent an imminent hazard resulting from its continued use.
An emergency suspension takes effect immediately; under an ordinary suspension
a registrant can request a hearing before the suspension goes into effect.
Such a hearing process might take six months.

Suspension Culture: Cells growing in a liquid nutrient medium.

Swamp: A type of wetland dominated by woody vegetation but without
appreciable peat deposits. Swamps may be fresh or salt water and tidal
or non-tidal. (See: wetlands.)

Synergism: An interaction of two or more chemicals that results
in an effect greater than the sum of their separate effects.